phil38
Thrash Merchant
Posts: 426
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Post by phil38 on Sept 10, 2014 23:04:18 GMT 1
Any one got an idea if what an N2 should do flat out? Pretty sure mine is well down on power.
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Post by cb250g5 on Sept 11, 2014 2:07:18 GMT 1
Without the fairing, around 100 is all you'll see, unless you start lying on the tank & holding the fork legs etc.
You're probably a bit heavier than back in the day as well.
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Post by raider18 on Sept 11, 2014 4:25:07 GMT 1
there was only around 5mph in it between a f2 & n2
f2 being the quicker at 115 ish flat tabs
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Post by JonW on Sept 11, 2014 7:23:18 GMT 1
what it will do and what the speedo says... well...  |
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phil38
Thrash Merchant
Posts: 426
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Post by phil38 on Sept 11, 2014 12:25:07 GMT 1
OK, it does 90mph flat out (that's without holding the forks, but I'm not a biffa!)
Just done a dyno run at it's only putting out 37hp....
Engine has been rebuilt (crank seals, honed, new rings, refurbished power valves, (bushes seals etc.), carbs balanced, slides do open fully, run in carefully for 300 miles.
I'll try to get the dyno plots out, but my suspicion is the PVs are not working (either not moving atall or going the wrong way). PVs were set up as per the book and cycle correctly when the ignition switches on - I guess that doesn't necessary mean they are moving with the bike running. I guess the PV controller could be knackered?
Bike is completely standard and runs very well, revs out to 9500 (on the dyno in 3rd & 4th)
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Post by muttsnuts on Sept 11, 2014 12:48:03 GMT 1
if you suspect the PV's, then the easiest way to check that is to jam them wide open, you'll lose some bottom end, but you'll be able to tell if that's your problem as it will be much better on WOT (Wide Open Throttle)
what air filter/air box config are you running?, I've had a few few come in running really badly due to after market air filters, took them out and it transformed the bike !
HTH
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phil38
Thrash Merchant
Posts: 426
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Post by phil38 on Sept 11, 2014 13:39:46 GMT 1
if you suspect the PV's, then the easiest way to check that is to jam them wide open, you'll lose some bottom end, but you'll be able to tell if that's your problem as it will be much better on WOT (Wide Open Throttle) what air filter/air box config are you running?, I've had a few few come in running really badly due to after market air filters, took them out and it transformed the bike ! HTH Everything is standard, air box with snorkel and gen yam filter, not drilled. I think I'll take the exh pipes of and check the PV positions. How would you jam it wide open for a test ? |
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Post by muttsnuts on Sept 11, 2014 13:44:44 GMT 1
just remove the cables and turn the valves so that the exhaust ports are fully open, you can test it like that, the valves generally stay open unless they are like a c**k in a shirt sleeve, in which case they are needing attention anyway !
or just rug something up to keep them open, I tend to just test them as above, not had a problem yet
PS - I'd be taking the snorkel out, it makes a big difference, also, have you considered if your exhaust are coked up ?
HTH
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phil38
Thrash Merchant
Posts: 426
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Post by phil38 on Sept 11, 2014 14:34:59 GMT 1
Cheers for the reply.
Exh are clean. Used the hot air gun method.
I wanted to start from completely standard and make sure the bike runs as yamaha intended. One I get past that point I may start fiddling. Set of microns hanging in the garage may be part of the plan eventually!
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Post by cb250g5 on Sept 12, 2014 2:18:18 GMT 1
Just take the L H powervalve cover off & rev it to 7-8000 RPM in neutral.
If there's no movement of the valves / cables, there's a clue....
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phil38
Thrash Merchant
Posts: 426
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Post by phil38 on Sept 12, 2014 6:42:30 GMT 1
Just take the L H powervalve cover off & rev it to 7-8000 RPM in neutral. If there's no movement of the valves / cables, there's a clue.... Why didn't I think of that!? |
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Post by stusco on Sept 12, 2014 15:06:57 GMT 1
Any one got an idea if what an N2 should do flat out? Pretty sure mine is well down on power. Off the clock |
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phil38
Thrash Merchant
Posts: 426
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Post by phil38 on Sept 13, 2014 14:52:17 GMT 1
Well, PV is all ok. Have also done a compression test which show both sides identical at 95psi, which may be on the low side but it is on std bore although honed and new rikken rings.
In the process of dismantling it, I noticed the block connector for the oil pump level sensor was right across the intake snorkel. I moved the cable to run round the other side of the filler cap. …
Now does 105, possible more but I ran it of road. Weirdly, the clutch slip I had a couple of months ago seems to have gone away!
So 10-15 mph on top speed, must be at least 10hp I'd guess.
Back on the Dyno next week then!
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